This invention relates to a manual operator for a pushbutton control device and more particularly to such an operator including a cover mounted on the control device and an actuator that has nonoperating and operating positions for protecting the pushbutton and depressing the pushbutton.
Pushbutton control devices are commonly used in operator-controlled machines. These machines often require that the start and end of machine operations are only at definite predetermined times under manual control of the machine operator. The control devices are arranged so that the machine will operate only during the time that the pushbutton is depressed.
Prior art solutions include protective guards or shields for protecting a pushbutton and upon displacement of protective means the pushbutton is exposed for manual operation. For example, in U.S. Pat. No. 2,659,780 a safety appliance for switches is disclosed including a flat guard which is hinged at one side to normally overlie a starting pushbutton of a machine control switch. The free end of the guard is swung away from the control switch to expose the pushbutton for its operation. An inwardly directed projection of the guard prevents the guard from being pressed inwardly against the pushbutton. In U.S. Pat. No. 2,370,877 a sheet metal shield is pivotally mounted so that when it is held in a raised position it overlies a pushbutton. Operation of the pushbutton is prevented. When the free-swinging end is released, the shield drops to an exposed position so that the pushbutton may be manually operated. In both of the aforementioned patents, the guard or shield only protects the pushbutton and is not utilized to effect intended operation of the pushbutton.
In U.S. Pat. No. 1,801,228 a pushbutton station having both a start and a stop bushbutton includes a hinged plate which when swung away from the housing of the station permits manual operation of either pushbutton. When the plate is raised and swung inwardly to a protecting state, the plate overlies the start pushbutton to prevent its operation. Concurrently, an inwardly projecting log of the plate depresses and operates the stop pushbutton with the plate in the operating state. The start pushbutton can always be operated when the guard is left down and is in the inoperative state. Neither one of the start or stop pushbuttons is both protected nor operated by alternate positions of the guard.
Accordingly, it is desirable that a pushbutton control device be protected from accidental or unintentional operation. It is further desired that a machine associated with the control device be actuated only upon deliberate and intended action by the machine operator that causes the pushbutton to be depressed. These and other desired features of a manual pushbutton operator are provided in accordance with the present invention.